'For most people who have seasonal affective disorder, autumn and winter are the low points, the time when depression becomes really difficult to negotiate.' Photograph: Andrew Fox/Alamy

It's a battle that starts at this time every year, right when the weather changes from mostly sunny and warm to grey and cold. My normal high energy and good spirits shift into exhaustion and biting irritation with the smallest problems. And as the longer days of autumn shorten to the all-to brief days of winter, everything gets worse. I can't get out of bed without relentless prodding from my partner, my brain is a cloud of fogginess that even constant coffee drinking can't clear, and once the clock change comes, depression settles over my world like a stifling blanket I can't throw off.

For most of my life, I didn't know why this happened to me every year. It wasn't until I went to a conference in Arizona during the winter and felt a massive surge of energy flood through me – as if I had taken a handful of antidepressants – that I considered something might be wrong. The yearly cycle was so gradual, so insidious, it seemed like that was just the way life was.

What I have is called seasonal affective disorder (Sad). Sad is a depressive disorder triggered by a lack of sunlight. Although spring and summer may act as triggers, for most people, autumn and winter are the low points, the time when depression becomes really difficult to negotiate. Of course, those who live farther from the equator are more often affected, but those in sunny regions can be, too, due to jobs or living conditions that require spending the majority of the day inside.

Although Sad is an illness that major health organisations recognise, far too many people go undiagnosed. There are many reasons for this, but perhaps the biggest are wrapped around the social stigma that is so intimately connected to depression. Depression, despite decades of work by awareness organisations, still has "laziness" associated with it. Some think that if you'd just change your point of view, get out for a walk, eat properly, talk with friends, not isolate yourself, get back to work etc – you'd feel better. Not so.

The idea that depression could fade in and out according to the weather just rings as another "excuse" that people with depression are accused of making. And, unfortunately, people living in the middle of untreated Sad are often simply unable to deal with the accusations and ignorance that comes from the lack of proper education. Debilitating exhaustion and unclear thinking make it impossible to even think about more drastic actions such as suicide. Sufferers often simply don't have the energy to pull a suicide off until spring rolls around. Is it any wonder, then, they prefer to do what they can to hide their illness, to grin and bear it, rather than get a diagnosis or try to explain it to those who are uneducated?

Social identity also proves to be a barrier to Sad treatment. I was in my 30s before I was diagnosed, and it only came after finally admitting to myself that my attempts to "fake it till I made it" just weren't going as well as I thought they were. To my surprise, I found myself almost unreasonably upset about how my identity as a worker was affected by the diagnosis. I come from an immigrant community that prides itself on being good workers. We justify our existence in the US based on our ability to be productive. What did this diagnosis mean for that identity, for my relationship with my community?

It turns out my struggles with identity were not new or particular to my community. Social stigma around Sad and depression plays out in many different ways for each community affected by it. Sad, like depression, is something that affects people regardless of their social identity.

Addressing the stigma attached to depression and Sad also makes it easier for people to get the appropriate treatment. Light boxes, the treatment method most prescribed by doctors for people with Sad, have few side-effects and really do make a difference.

Last winter was my first full season using a light box and I often found myself marvelling that there are enjoyable things to do during the winter. I learned how to cross-country ski and didn't miss any work days. While living can still be a struggle for me, I am generally no longer overwhelmed by complete indifference or exhaustion. Life doesn't need to stop every winter for so many people, but we need to understand the reasons why it does before things can change.

• This piece was commissioned after it was suggested by alisdaircameron and Sipech on a You tell us thread

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